Despite the economic problems, Greece, which does not refrain from its armament activities, has taken action to manufacture domestic assault rifles with local opportunities.

AOR Design Team introduced the new infantry rifle design to the personnel of different ranks from the Hellenic Army General Staff. It was stated that the design activities started in September 2019 and the studies completed in March 2020, while the presentation was delayed due to the worldwide effective COVID-19.

The assault rifle, named as M21; has two main variants called M21-5 firing 5.56x45mm NATO rounds and M21-7 using 7.62x51mm NATO ammunition. Thanks to its modular design, the M21-5 model is a customizable weapon for close quarter battle, which has 10.5 inches (267 mm) barrel. There is also 14.5 inches (368 mm) barrelled carbine variant. It was announced that the rifle, which has a standard barrel length of 16 inches (406 mm), will also has DMR model with an 18 inches (457 mm) barrel. In this way, a single solution is offered for all requirements from the standard infantry to the level of special forces. M21, which is stated to be suitable for ambidextrous use, has a wide trigger guard that enables the use of the gun with gloves. While it is aimed to increase the accuracy of the weapon with the free floating barrel, the outer coating is said to have a structure that will reduce the infrared trace. In the shared design images, it was seen that the M21 was equipped with an adjustable buttstock. The rifle, which seems to have a folding iron sight, is equipped with MIL-STD 1913 Picatinny rail on the receiver and also partially under the barrel. The handguard of the M21, which is estimated to have an AR mechanism, is M-LOK for the use of different equipment.